The present invention relates to the shaping and curing of rubber articles and is especially useful in eliminating or effectively reducing flash formed on a pneumatic tire during the molding and vulcanizing process.
Tires are made today by forcing a previously built uncured tire carcass to conform to a mold cavity and then subjecting the tire to heat and pressure to vulcanize the rubber. The mold is comprised of two or more sections, each of which is provided with a number of vent holes which permit gas to escape from the mold cavity during molding and vulcanization of the tire. The rubbery material normally flows into the vent holes and spaces between the abutting mold sections during the shaping and vulcanizing operation causing the formation of unwanted rubber protuberances on the outer molded surface of the tire. The long rubber protuberances or projections formed in the vent holes are commonly referred to as vents. The narrow rubbery ridges formed in the joints of abutting mold sections are commonly referred to as flash. These vents and flash are undesirable from an aesthetic standpoint. Moreover, flash extending across the tread of a tire can generate excessive tread noise during operation. The completed tire is therefore normally moved to a station where any vents or flash are mechanically trimmed from the tire.